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A series of seventeen taxonomically diverse plant extracts rich in phenolic materials, including condensed and hydrolysable tannins, have been subjected to a series of biochemical analyses in an attempt to gather ecologically significant information about their interaction with proteins and amino acids. Methods employed were (i) protein-precipitation, using(More)
The cricket, Gryllus rubens (Orthoptera, Gryllidae), exists in natural populations as either a fully-winged (LW), flight-capable morph or as a short-winged (SW) morph that cannot fly. The SW morph is substantially more fecund than the LW morph. In this study we report on the physiological basis of this trade-off between flight capability and fecundity.(More)
We present the results of a 5-year examination of variation in the stable carbon isotope composition (δ) of three C3 graminoid species from a Sandhills prairie: Agropyron smithii, Carex heliophila and Stipa comata. Although consistent species-specific patterns for mean δ were seen, there was also significant and substantial among-year and within-season(More)
The biochemical basis for considering tannins as digestion inhibitors has been reexamined. Both stimulatory and inhibitory effects of tannins on tryptic hydrolysis are reported. We show how stimulation may result from tannin-induced structural changes in the substrate protein, effectively denaturing it. The surfactant and bile constituent cholic acid also(More)
The allelochemic activity of the polyphenolics isolated from the leaves of four west African rain-forest plants,Acacia pennata, Cynometra leonensis, Diospyros thomasii, andTrema guineensis, was examined by means of protein precipitation experiments to estimate their specific activity as precipitants. Results indicated that light-induced phenol synthesis in(More)
Nutritional indices, triglyceride levels and flight muscle developmental profiles were compared between long-winged (LW) and short-winged (SW; flightless) morphs of the cricketsGryllus rubens Scudder andG. firmus Scudder. This was done to identify potential physiological costs of flight capability in adults. The LW morph of each species converted a lower(More)
Acting simultaneously or sequentially, plants encounter multiple stresses from combined abiotic and biotic factors that result in decreased growth and internal reallocation of resources. The plant stress hypothesis predicts that environmental stresses on plants decrease plant resistance to insect herbivory by altering biochemical source–sink relationships(More)
Because of their potential as antiherbivore defenses, plant phenolics elicit considerable attention. We made quantitative and qualitative analyses of phenolics, alkaloids, cyanogenic glycosides, and saponins in the dominant graminoids of a Nebraska Sandhills prairie. We examined the foliage of seven species:Agropyron smithii Rydb.,Andropogon hallii(More)
The concept of protein precipitation potential has recently been introduced by Wisdom et al. (1987) as a means to combine chemical and protein precipitation assays of tannins for ecological studies. The definition of protein precipitation potential was not theoretically rigorous, and data analysis was obscure. Our attempts to repeat the tannin extraction(More)